Discovery of anti-metastatic drugs is of immense clinical significance as metastasis is responsible for 90% of all cancer deaths. Here we report the inhibitory effect of a bis schiff base (M2) on cancer cell migration and invasion in vitro and in vivo. M2 has shown good solubility and permeability across the intestinal cell wall and hence can be classified as BCS (Biopharmaceutical classification system) class I. Microarray studies identified a long non coding intergenic RNA, LINC00273 as a novel molecular target of M2. We report that LINC00273 harbors a unique (4n-1) parallel G-Quadruplex structure in its promoter as validated by DMS footprint. M2 is proposed to stabilize this G-quadruplex structure resulting in the down-regulation of LINC00273 expression. Dual Luciferase reporter assay also suggests inhibition of LINC00273 promoter activity by M2. Involvement of this linc in metastasis is proven by siRNA and shRNA mediated knock down of LINC00273 in vitro and in vivo in nude mice which significantly decelerates cancer cell migration and invasion and also makes the cells unresponsive to TGF-β's pro-metastatic effects. Furthermore, the real time expression of LINC00273 in thirty seven human clinical samples is found to be positively correlated with the histopathological staging of metastasis.

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A stable intermediate dimeric G-rich form as a precursor of tetrameric G-quadruplex structures has been detected via MALDI-TOF spectrometry. Molecular dynamics simulation offered detailed insights at the atomic level, assigning reverse Watson-Crick G-G base pairing (not Hoogsteen) in the G-rich dimer. In support of this, cisplatin formed a stable adduct by binding to the dimeric G-rich structure, eliminating the possibility of G-G Hoogsteen hydrogen bond formation.